The studies in this project will examine the roles of human papillomavirus gene expression in changes in the phenotype of epithelial cells infected with this virus. Organotypic cultures will be used as the in vitro method of choice since, in this tissue culture system, we can define the effect of expression of individual virus genes on the replication, stratification, keratinization and cornification of epithelial cells. Viral and cellular gene expression will be initially assessed by in situ hybridization methods and antigen detection on sections prepared from the organotypic cultures. Further studies will employ extraction of nucleic acids and proteins for examination by Southern and Northern blotting, polymerase chain reaction and radioimmune precipitation. Chemical and hormonal factors which may interact with HPV in the development of infection and progression of disease will also be incorporated in these studies. The factors involved in blocks to replication of HPVs which cannot currently be grown in vitro, will be examined.